fix #3479 (typos in example-code in QueryBuilder)
fix #3479 (typos in example-code in QueryBuilder)

fix two typos in QueryBuilder, on of them reported in #3479
lcobucci/dbal,doctrine/dbal,doctrine/dbal,mikeSimonson/dbal,mikeSimonson/dbal,BenMorel/dbal,BenMorel/dbal,drieschel/dbal,lcobucci/dbal,drieschel/dbal